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The inclusion of zirconium precursors to prepare organosilane solgel coatings improves the corrosion protection performance of the coatings on aluminium and steel. The inherent differences in the hydrolysis rates of the silane and zirconium precursors, various ligands were used to control the hydrolysis by decreasing the number of reactive alkoxide group. Hybrid sols were synthesised using 3-(trimethoxysilyl) propylmethacrylate (MAPTMS) and zirconium n-propoxide chelated with organic ligands including different organic acids, acetyl acetone and 2 2’ bipyridyl. The effects of zirconia inclusion on the properties of the coatings were compared on the aerospace alloy AA 2024-T3.
Electrochemical analysis and salt spray exposure characterized the corrosion protective properties. The results indicate that acid chelated systems possess better corrosion protection when compared to the other ligands, due to smaller zirconium nanoparticles being formed. In particular superior performance was displayed by the coatings involving 3,4 diaminobenzoic acid (DABA) due to inherent anticorrosive properties.
Varma, PCR.,(2015) Corrosion Protection Properties of Various Ligand Modified Organic Inorganic Hybrid Coating on AA 2024-T3, ECS Transactions, 24 (1) 231-246